Department of Chemistry and Biochemistry, University of South Carolina , Columbia, South Carolina 29208, United States.
Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
J Am Chem Soc. 2017 Nov 22;139(46):16852-16861. doi: 10.1021/jacs.7b09496. Epub 2017 Nov 8.
Growing necessity for efficient nuclear waste management is a driving force for development of alternative architectures toward fundamental understanding of mechanisms involved in actinide (An) integration inside extended structures. In this manuscript, metal-organic frameworks (MOFs) were investigated as a model system for engineering radionuclide containing materials through utilization of unprecedented MOF modularity, which cannot be replicated in any other type of materials. Through the implementation of recent synthetic advances in the MOF field, hierarchical complexity of An-materials was built stepwise, which was only feasible due to preparation of the first examples of actinide-based frameworks with "unsaturated" metal nodes. The first successful attempts of solid-state metathesis and metal node extension in An-MOFs are reported, and the results of the former approach revealed drastic differences in chemical behavior of extended structures versus molecular species. Successful utilization of MOF modularity also allowed us to structurally characterize the first example of bimetallic An-An nodes. To the best of our knowledge, through combination of solid-state metathesis, guest incorporation, and capping linker installation, we were able to achieve the highest Th wt % in mono- and biactinide frameworks with minimal structural density. Overall, the combination of a multistep synthetic approach with homogeneous actinide distribution and moderate solvothermal conditions could make MOFs an exceptionally powerful tool to address fundamental questions responsible for chemical behavior of An-based extended structures and, therefore, shed light on possible optimization of nuclear waste administration.
对高效核废料管理的迫切需求是开发替代架构的驱动力，目的是深入理解锕系元素（An）在扩展结构中整合的机制。在本文中，金属-有机骨架（MOFs）被作为一种模型体系进行研究，通过利用前所未有的 MOF 模块性来设计包含放射性核素的材料，这在任何其他类型的材料中都无法复制。通过在 MOF 领域实施最近的合成进展，逐步构建了 An 材料的分级复杂性，这仅由于制备了具有“不饱和”金属节点的基于 An 的框架的第一个实例才成为可能。首次成功尝试了在 An-MOFs 中进行固相配位转化和金属节点扩展，前者的结果揭示了扩展结构与分子物种之间在化学行为上的显著差异。MOF 模块性的成功利用还使我们能够对第一个双金属 An-An 节点的结构进行表征。据我们所知，通过固相配位转化、客体掺入和封端连接体安装的组合，我们能够在单核和双锕系元素框架中以最小的结构密度实现最高的 Th 重量百分比。总的来说，多步合成方法与均匀的锕系元素分布和适度的溶剂热条件相结合，可能使 MOFs 成为解决负责 An 基扩展结构化学行为的基本问题的极其强大的工具，从而为核废料管理的可能优化提供了启示。
